Related papers: A narrow "peanut" pentaquark
Diquarks are found to have the right degrees of freedom to describe the tetraquark poles in hidden-charm to open-charm meson-meson amplitudes. Compact tetraquarks result as intermediate states in non-planar diagrams of the 1/N expansion and…
The narrow width of the exotic narrow baryon resonance $\Theta^+$ might be explained by mixing between the two nearly degenerate states that arise in models with two diquarks and an antiquark. The only open $\Theta^+$ decay channel is $KN$.…
The stability of strange pentaquarks $uudd\bar s$ is studied in a constituent quark model based on a flavor-spin hyperfine interaction between quarks. With this interaction model, which schematically represents the Goldstone boson exchange…
We study spin 1/2 isoscalar and isovector, even and odd parity candidates for the $\Theta^+(1540)$ pentaquark particle using large scale lattice QCD simulations. Previous lattice works led to inconclusive results because so far it has not…
The earlier search at HERMES for narrow baryon states excited in quasi-real photoproduction, decaying through the channel $pK_S^0\rightarrow p\pi^+\pi^-$, has been extended with improved decay-particle reconstruction, more advanced particle…
The pentaquark state recently discovered has been discussed based on various quark model calculations. Odd parity for the state can not be ruled out theoretically because contributions related to non-trivial color structures have not been…
The pentaquarks are exotic baryons formed of four quarks and an antiquarks. Their existence has been discussed in the literature over the last 30 years or more, first in connection with kaon nucleon scattering data. The subject has been…
The structure of the pentaquark state uudd-sbar is studied in the chiral SU(3) quark model as well as in the extended chiral SU(3) quark model, in which the vector meson exchanges are included. Four configurations of JP=1/2- and four of…
We discuss the implications of the suggested interpretation of the recently reported narrow pi N resonance (width \approx 25 MeV at 1680 MeV) as a pentaquark in the same multiplet as the Theta+. We consider a diquark-triquark pentaquark…
We study the possibility that at least one of the two pentaquark structures recently reported by LHCb can be described as a compact pentaquark state, and we give predictions for new channels that can be studied by the experimentalists if…
With the heavy quark symmetry and spin rearrangement scheme, we study the strong decay behavior of the hidden-charm pentaquark states with $J^P={\frac{3}{2}}^{\pm}, {\frac{5}{2}}^{\pm}$ assuming they are molecular candidates composed of…
QCD instantons are known to produce deeply bound diquarks which may be used as building blocks in the formation of multiquark states, in particular pentaquarks and dibaryons. We suggest a simple model in which the lowest scalar diquark (and…
The experimental signature of an S=+1 baryon of mass 1540 MeV and width 10-25 MeV has led to speculation that this is an exotic baryon consisting of 4 quarks and 1 antiquark lying at the top of a $\bar{10}$ SU(3) multiplet. The observed…
We investigate medium modifications of the pentaquark $\Theta^+$ in dense medium, taking into account different parities of the exotic $\Theta^+$ baryon. We find that the chemical potential of the $\Theta^+$ is shifted in a…
We present a very general argument that the analogue of a heavy pentaquark (a state with the quantum numbers of a baryon combined with an additional light quark and a heavy antiquark) must exist as a particle stable under strong…
In these lecture notes I discuss an algebraic model of baryons and pentaquarks, in particular a stringlike collective model is considered in which the radial excitations of baryons and pentaquarks are interpreted as rotations and vibrations…
We have investigated uudd\sbar pentaquarks by employing quark models with the meson exchange and the effective gluon exchange as qq and q\qbar interactions. The system for five quarks is dynamically solved; two quarks are allowed to have a…
We examine several assignments of spin and parity for the pentaquark Theta+ state (J^P=1/2^{+,-}, 3/2^{+,-}) in connection with phenomenology of known baryon resonances, using a general framework based on the flavor symmetry. Assuming that…
By assuming SU(6)_cs symmetry for pentaquark decays one finds a selection rule, which strongly reduces the number of states able to decay into a baryon and a meson final state and allows an intriguing identification for the Theta^+ particle…
Considering quantum chromodynamics in the consistent limit of simultaneous correlated increase of the number of colours, $N_{\rm c}$, beyond bounds and decrease of the strong coupling to zero allows for solid statements about qualitative…